In order to improve the portability of portable electronic equipment such as the portable telephone and notebook computer, a battery pack containing rechargeable batteries is used as the power supply. The battery pack is either built-into the electronic equipment in a fixed manner or is attached in a removable fashion. A battery pack attached to electronic equipment in a removable fashion can be swapped for a fully charged battery pack when it has discharged. The discharged battery pack can also be detached from the electronic equipment and recharged. Finally, a detachable battery pack can easily be separated from the electronic equipment when it is disposed of. For this reason, a detachable battery pack containing a harmful substance such as cadmium has the feature that it can be disposed of separately from the electronic equipment.
Electronic equipment with a detachable battery pack can be conveniently used if the battery pack can be recharged while attached to the electronic equipment. This is because the battery pack can be recharged by setting the electronic equipment in a charging stand. Electronic equipment which realizes this feature is disclosed in Japanese Patent Publication No. 3-167768 issued in 1991.
Turning to FIGS. 6 and 7, this disclosure is illustrated by the Handy Terminal electronic equipment 72 with detachable battery pack 71 and charging stand 73. The Handy Terminal 72 in these figures is set on the charging stand 73 when not in use. When on the charging stand 73, the charging terminals (not illustrated) off the battery pack 71 are connected to the power supply terminals 74 of the charging stand 73 to recharge the battery pack 71. Consequently, when the Handy Terminal 72 is not in use, the battery pack 71 can be conveniently recharged without detachment.
For electronic equipment of this configuration, it is necessary to carry the charging stand along when traveling. This is because the charging stand is required to recharge discharged battery packs. If the charging stand is not carried along, the operating time of the electronic equipment is limited to the time to discharge the battery pack. However, carrying the bulky charging stand along with the electronic equipment is inconvenient. Often electronic equipment containing rechargeable batteries, such as the portable telephone, is used by carrying it with the user. In this case, also carrying a charging stand is extremely inconvenient. In order to lengthen electronic equipment operation time without carrying along a battery charger, large battery packs have been developed which can be substituted for small battery packs when traveling. When battery pack capacity is doubled, operating time is also doubled. However, it is difficult to estimate operating time when taking electronic equipment on a trip, and regardless of how large the battery pack is, it can still discharge completely leaving the equipment unusable. The first object of the present invention is to eliminate this drawback. Namely, a primary object of the present invention is to provide a battery charger, battery case, and electronic equipment wherein the electronic equipment can be used for long periods without carrying along a charging stand.
Further, convenience of use is achieved by allowing the battery pack to be recharged while attached to the electronic equipment or after separation from the electronic equipment. A battery pack can be recharged while attached to electronic equipment not in use, a completely discharged battery pack can be replaced with a fully charged one, and the completely discharged battery pack can then be recharged. However, realization of this configuration also requires a separate charging stand apart from the electronic equipment. For this reason, it is necessary to carry a charging stand along with the electronic equipment when traveling with the equipment. The second object off the present invention is to further eliminate this drawback. Specifically, another object of the present invention is to provide a battery charger, battery case, and electronic equipment wherein a battery pack can be recharged without carrying along the charging stand, and when necessary a battery pack can be recharged while attached to the electronic equipment or after being disconnected from the electronic equipment.